I don’t think it’s a big deal if someone who isn’t a journalist/author makes a grammar error when commenting on FB or Twitter. Most people probably post in a hurry and hit enter before looking at their text.
However, when posting a comment on a local, regional, or national media website, I think people should at least proofread their comments to ensure that they have used the correct word, e.g., accept not except.
Recently, on a local media website, I backed up a woman who had called out a poster on this error. Another commenter asked us if we though the man’s grammar mistake made his opinion “not valid”. No, of course his opinion is valid. But he probably could use a short refresher course in correct word usage.
This particular error is one of my pet peeves. I learned the difference between affect and effect in sixth grade English class. Thank you, Mrs. Grover.